In 1978, it was reported for the first time that ascopyrone P (structural formula: FIG. 1) was produced by pyrolysis of cellulose (refer to Shafizadeh, F., et al., Carbohydr. Res. 67, 433-447 (1978)). Thereafter, its three-dimensional structure was analyzed and revealed by 1H-NMR, 13C-NMR and infrared spectroscopy (IR).
Ascopyrone P (hereinafter referred to as APP) has been reported to have an antioxidant activity, an antibacterial activity and an ability of preventing browning (refer to WO00/56838, WO02/26060 and WO02/26061). It is a substance with very high functionality for which expectation has been increasingly raised lately. Further, it has also been reported that fungi of certain types in nature produce ascopyrone P (refer to M.-A. Baute, phytochemistry, 33, 41-45 (1993)).
A number of reports have been made on a method of preparing APP. In the case of a method of preparing APP by pyrolysis of cellulose, the yield of APP is as low as only about 1.4% with respect to cellulose which is a raw material, and a very complicated separation process is required in subsequent purification, thereby making it unrealistic to use this method for industrial production. Further, it has been reported that a number of compounds are produced from 1,5-D-anhydrofructose (hereinafter referred to as 1,5-AF) in aqueous strong alkali solution and APP is one of intermediates produced in the production process of these compounds (refer to Ahmad, T., Phd Thesis, The Swedish University of Agricultural Sciences, Sweden (1995)). However, APP is an intermediate under this condition, and a method of terminating the reaction by APP and a method of preparing APP as a final product are not described.
Although it has also been reported that APP can be enzymtically synthesized by crude extract of Pezizales orders (e.g. Picaria leiocarpa and Anthracobia melaloma) and Tuberales orders (e.g. Tuber melanosporum) to act on 1,5-AF, this method has been used only for preparation in milligrams. This preparation method shows a low yield and low efficiency despite taking considerable time and effort. Therefore, it is not suited for industrial use.
Recently, as a production method of APP using enzyme, a method with specifically defined production conditions has been applied for patent (refer to WO03/038085, WO03/038107 and WO03/038084). However, this method requires a long time for an enzyme reaction and needs to spend time for production of enzyme.
Meanwhile, 1,5-AF is sugar that can be prepared by degradation α-1,4-glucan such as starch by α-1,4-glucan lyase and can be mass-produced at low cost. Use of this sugar as an antibacterial agent (refer to JP-A 2001-89377 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”)), an antioxidant (refer to JP-A 9-505988) and a colorant (refer to JP-A2002-27945) has already been proposed.